Furnace or boiler wall construction



Nov, 12, 1940.

4T. E. MURRAY, V.1R URNAGE OR BOILER WALL CONSTRUCTION Filed March 2, 19574 2 Sheets--SheecA l INVENT OR.

Arc/A2 EOM/WEMPE f5 ATTORNEYS Nov. 12, 1940.

T. E. MURRAY, JR

FURNACE OR BOILER WALL CONSTRUCTION Filed March 2, 193'? 2 Sheets-Sheet 2 lNvENTOR. 777/0/14//5 'a/P/PAKJ? Patented Nov. 12, 1940 UNITED STATES PATENT OFFICE FURNACE OR BOILER WALL UONSTRUCTION Claims.

In a previous patent to Thomas E. Murray,

No. 2,029,437, of February 4, 1936, there is described a boiler wall construction comprising upright tubes spaced apart with metal members 5 united to the tubes and extending substantially across the spaces between them, this combination constituting the entire thickness of a wall of the furnace, or being supplemented by refractory and insulating material; and numerous other patents have been granted for variants of this construction and of the separate units.

The present invention is directed to an improved wall construction of the same general class for furnaces or boilers, stills and ,other heat exchangers and to improved units of such construction, which units are adapted for other uses also.

The accompanying drawings illustrate embodiments of the invention.

Figs. l and 2 are, respectively, a horizontal section of a boiler wall and an inside face view of the upper portion thereof; Fig. 3 is an enlarged and extended illustration of a lower portion of one of the units in Fig. 2; Fig. 4 is a cross-section on the line 4-4 of Fig. 3; Figs. 5 to 9 inclusive are diagrams similar to Fig. 4 showing alternative constructions; Figs. and 11 are a plan and elevation of another alternative construction. l

Referring to Figs. 1 to 4, a boiler wallis shown with an inner lining or wall or screen comprising tubes I with projections 2 extending laterally outward in a manner similar to the wall ofthe aforesaid Murray patent.

In the present case, the tubes, being spaced apart, have the projections 2 extending suiciently to practically cover the width of the spaces between them. 'I'hey may even overlap, as shown, in the above patent, or they may extend only partially over such spaces. Such tubular units may constitute the full thickness of Vthe wall, or may be used with an outside wall structure of Aany suitable material. As illustrated, they are used with outside refractoryl 55 vided also with protection over their faces exposed to the fire, such protection being composed of pre-formed metal pieces welded thereto. Such protection for the faces of the tubes may be provided withthe lateral projections 2 shown or without such projections and may be provided 5 over any desired portion or over the entire length of the tube; and where face protection is provided over only a portion of the length of the tube, the remaining portion may be bare or may be provided with lateral projections either in 10 the form shown at 2, or in any numerous other `available forms.

These variations may depend on whether the furnace is grate red or is iired with -fuel in suspension, such as powdered coal, oil or gas and 15 ,upon the design and use of the furnace. The designs illustrated are generally, but not exclusively, for boiler furnaces,in which the tubes are connected into the circulation of the boiler either for the direct generation of steam, or as parts of superheaters or economizers, or for like uses.

As illustrated, the tubes are assumed to be ordinary seamless drawn boiler tubes of soft steel of three or four inches in diameter and` comparatively great length, the other dimensions being as illustrated on the drawings by comparison with afour inch diameter; but the invention is also applicable to tubes of special. steels and other metals and of other kinds and dimensions. 30

In Figs. 3 and 4, the ns or lateral projections 2 are assumed to continue throughout the length of the tube. In additiongextending over the lower part of the tube and over the face of it which is to be exposed to the fire there are metal exten- -35 sions `1 and 8. These are preformed small plates or strips, the length (meaning the dimension parallel to the axis of the tube) being the same as that of the outward projections 2 and registering with the latter. These pieces are welded at their 40 ends to the tube while in the dotted line positions indicated at la and 8 8, Fig. 4, and are then bent around over the face of the tube.

By making the pieces initially of the same size as the ns 2, and pairing them in the manner illustrated, they can be welded at their ends to the tube .by known andA economical resistance welding methods which do not weaken the tube. When bent to their final position, they protect the face of the tube. The spaces 8 and l0 be- 50 tween these protecting members and the tube are air spaces, whichrestrict the `conduction of heat and thus protect the re from excessive cooling and also protect the tubefrom burning out, where the re is extremely hot. This is true to an extent even where the members 'I and 8 contact with the tube, as long as they are not welded thereto at such points.

Such metal extensions over the face of the tube may be used with or without the lateral projections 2', for the protection of the tube as stated and in various other arrangements including those described below.

Fig. 5 illustrates a variant of Fig. 4, in which a pair of the overlying members II are butt welded at their ends to the center of the portion of the tube face to be protected and then bent over to their nal positions. This gure also illustrates an alternative, which may be adopted or not, namely, the projection welding ofthe outer portions of the members II to the tube, as indicated at the points I2 and by the depressions I3 in their faces formed by the welding tools.

In following the arrangements of Figs. 4 and 5, two adjacent pieces will be welded at one operation. According to'Fig. 4, the pair at the two sides and the pair at the front may all be welded simultaneously since there is no interference with the pressing operations necessary in taking up and extruding metal at the weld. Similarly for Fig. 5, the single pieces at the sides and the pair of pieces at the front may be welded all at one operation, or the two side pieces first and the two front pieces afterwards.

Or, as shown in Fig. 6, a single piece may be used to provide projections 1,5 at one side and I6 overlying about half of the front. Two such pieces are butt welded atthe front close together,

as at 11, and then bent around to contact withthe tube at points "I8, being butt welded there or not, as preferred. Thereafter, they are firmly held by deposited weld metal 'I9 between the inner ends of the parts 'I5 and the tube.

According to Fig. 7, a single piece rof the shape indicated in dotted lines at 80, being a straight flat strip with a central rib, is butt welded at the rib to form a joint 8| with the tube and is then bent around at both sides `to form the central portion 82 overlying the face and the lateral extensions 83 which are further attached by deposited metal 84. 'I'he lateral extensions 83 may be carried back to a line passing through the center of the tube, like the extensions 2 of Fig. 4, for example, and the parts 82 may be butt welded to the tube as indicated at 'I8 in Fig. 6, if preferred.

Fig. 8 illustrates still another arrangement using two pieces of angular shape with arms 85 and 86 and a small projection 8l, which is butt According to Fig. 9, the lateral outwardly pron jecting fins I4 are mounted not at opposite ends of a diameter, but between the innermost point of the circumference 'of the tube and the extreme lateral points. After being butt welded, they are I bent back to parallelism along the line of the wall. The face-covering members I5 are paired with the ns I4, in the welding operation and are then bent toward each other over the inter- Y mediate face of thetubes. The two members I4 and I5can be butt Welded to the tube at one operation, the pair at one side of the tubev being welded either simultaneously with or subsequently to those at the other side.

The above face-covering members have been illustrated as corresponding in vertical dimensions with the outward lateral projections and registering in horizontal alignment therewith. They are not necessarily` of this dimension and relative location however. While in part they and the lateral projections combine to serve one function, namely, increased surface exposure; yet they serve other functions, which are independent of those served by the lateral extensions. They protect the tube itself by positioning over its face an extra thickness of metal.

Efforts have been made tosecure such protection by the casting of an extrathicknessof metal onthe fire side of the tube. The molten metal, however, tends to partly melt the original tube wall and reduce its strength. The molten metal is also a very diierent material structurally from thev They are, or can be, made of the identical steel which is used for the tubing. They can be applied with comparatively simple equipment and at comparatively small expense. And they have the great advantage that their extent can' be regulated with exactness. 'By the size and the spacing of the pieces, they can be made to cover more or less of the surface of the tube. The

.thickness of the pieces, the extent of their welded union and of their separated area and the air space between them when that is desired, can all be determined with accuracy.

In welding small pieces separately, there is no such temperature strain induced in the tube as is encountered in any effort to make a weld 'which is continuous along the full length of the tube or any great portion of such length. Similarly, in use, there is such a distribution of the temperature strains as to avoid severe cumulative stresses in the tube and projections, whichotherwise might rupture them and would decrease their resistance to oxidation or burning.

An example of an arrangement in which the outward projections and the surface covering parts are not in longitudinal alignment is shown in Figs. 10 and 11. Here simple rectangular rods, shown dotted at 14, are welded in two longitudinal lines at diametrically opposite points long the tube. The alternate rods are bent around over the front of the tube I as at 12 (with additional spot or projection or deposit welding if desired). The remaining projections are then pressed out to a flat shape, in which operation they are spread so as to bring their edges fairly close together as in Fig. 11. 'I hese projections in the finished shape are shown in full lines, as at 13.

The particular methods described for making these tubular units have substantial advantages. They involve comparatively simple welding operations. They are adapted to weld metals having the same welding characteristics or properties. curacy and very economically, the extent to which the tubing is covered, in the extra thick-k ness as well as the circumferential and longitudinal dimensions, and of the area of the welded connection through which the heat is conducted between the extensions and the tube ard They permit determining with great acthe separation or spacing between the tube and the overlying metal. Other advantages are stated in detail above.

Numerous other modifications may be made by those skilled in the art without departing from the invention as defined in the following claims.

What I claim is: 1

1. A boiler having re box walls, of spaced water-circulating and heat-receiving tubes, said tubes each having two rows of ,heat-receiving wings welded to said tubes at closely spaced intervals lengthwise of the tubes, said rows of wings extending from opposite sides of said tubes in symmetrical arrangement relative to the center line of said tube substantially to ll the spaces between said tubes and covering pieces overlying and shielding the heat-receiving surfaces of said tubes facing said re box between said rows of heat-receiving wings and comprising wings each welded at one end to said tube at closely spaced intervals lengthwiseof said tube and bent near said welded. end to lie in closely spaced relation to the heat-receiving surface of said tube.

2. A boiler having fire box Walls of spaced water circulating'and heat-receiving tubes, said tubes each having two rows of heat-receiving wings welded to said tubes at closely spaced intervals lengthwise of the tubes, said rows of wings extending from opposite sides of said tubes in symmetrical arrangement relative to the center line of said tube substantially to iill the spaces between said tubes and covering pieces overlying and shielding the heat-receiving surfaces of said tubes facing said re box 'between said rows of heat-receiving wings, and comprising wings welded at one end to said tube between the wings of said rows of sidewlse projecting wings and bent near said welded end to lie in -closely spaced relation to the heat-'receiving surface of said tube.

3. The boiler of claim 1 in which the portions of said covering wings closely spaced from the tube Awalls are additionally welded directly to said walls.

4. The boiler of claim 1 in which the covering wings are welded to said tube adjacent to said heat receiving wings and extend away from said heat receiving wings over the surface of said tube.

5. The boiler of claim 1 in which the covering wings are welded to said tube at a distance from said heat receiving wings and extend over the surface of said tube toward said heat receiving wings.

THOMAS E. MURRAY, Jn. 

